4-Cyclo-propyl-1-(6'-de-oxy-1',2'-O-iso-propyl-idene-α-d-gluco-furanos-yl)-1H-1,2,3-triazole.

In the title compound, C14H21N3O5, the tetra-hydro-furan ring adopts an envelope conformation with the C atom bearing the substituent as the flap. The penta-furan-ose ring adopts a twisted conformation about the C-C bond fusing the rings. The dihedral angle between these rings (all atoms), which are cis fused, is 72.89 (14)°. The cyclo-propane ring is disordered over two orientations in a 0.576 (5):0.424 (5) ratio; the dihedral angles subtended to the triazole ring are 53.3 (11) and 46.6 (9)°, respectively. In the crystal, the mol-ecules are linked by O-H⋯N and O-H⋯O hydrogen bonds, generating (001) sheets. A weak C-H⋯O inter-action also occurs.

1,2:1',2'-Di-O-iso-propyl-idenedi-furan-ose-C12 higher carbon sugar.

In the title compound, C18H28O8, the five-membered ring with one O atom attached to the ethyl substituent has a twisted conformation about the C-O bond. The adjacent cis-fused ring with two O atoms also has a twisted conformation about one of the C-O bonds. The dihedral angle between these rings (all atoms) is 59.05 (12)°. The five-membered ring linked to the ethynyl susbtituent is twisted about a C-C bond; the cis-fused adjacent ring is twisted about a C-O bond [dihedral angle between the rings (all atoms) = 71.78 (12)°]. Two intra-molecular O-H⋯O hydrogen bonds occur. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds, generating [001] chains.

Effects of shipping emissions on cloud physical properties over coastal areas near Shanghai.

To investigate the effects of shipping aerosols on radiation, cloud physical properties, and near-surface PM2.5, four sensitive experiments with the WRF-Chem model were performed over coastal areas near Shanghai for July 2014. In general, the direct effect of shipping aerosols resulted in negative shortwave (SW) radiation forcing at the land surface. However, when considering the indirect effect, the downward SW radiation at the sea surface declined significantly. By the direct effect, shipping aerosols could modify cloud structure, resulting in a higher cloud base, lower cloud top, and shallower cloud depth. With the indirect effect included, both the cloud base and cloud top showed a declining trend over sea areas. The indirect effect of shipping aerosols was relatively more significant in influencing clouds. For example, the results revealed a 1.2% change of low cloud coverage from the indirect effect but only a 0.1% change due to the direct effect. Through their direct and indirect effects, shipping aerosols cause non-negligible impacts on precipitation, which are concentrated within light precipitation (<0.1 mm h-1). Finally, we concluded that after considering the shipping aerosols, the peak of the cloud droplet spectrum increases by about 50 cm-3/µm. It can be found that when the average volume radius of the cloud droplet is less than 2 µm, the number concentration of cloud droplets increases sharply, and when the average radius of the cloud drop is greater than 2 µm and less than 5 µm, the cloud droplet number concentration drops sharply.

Characteristics of ambient volatile organic compounds (VOCs) measured in Shanghai, China.

To better understand the characteristics of ambient abundance of volatile organic compounds (VOCs) in Shanghai, one of the biggest metropolis of China, VOCs were measured with a gas chromatography system equipped with a mass-selective detector (GC/MSD) from July 2006 to February 2010. An intensive measurement campaign was conducted (eight samples per day with a 3 hour interval) during May 2009. The comparison of ambient VOCs collected in different regions of Shanghai shows that the concentrations are slightly higher in the busy commercial area (28.9 ppbv at Xujiaui) than in the urban administrative area (24.3 ppbv at Pudong). However, during the intensive measurement period, the concentrations in the large steel industrial area (28.7 ppbv at Baoshan) were much higher than in the urban administrative area (18 ppbv at Pudong), especially for alkanes, alkenes, and toluene. The seasonal variations of ambient VOC concentrations measured at the Xujiahui sampling site indicate that the VOC concentrations are significantly affected by meteorological conditions (such as wind direction and precipitation). In addition, although alkanes are the most abundant VOCs at the Xujiahui measurement site, the most important VOCs contributing to ozone formation potential (OFP) are aromatics, accounting for 57% of the total OFP. The diurnal variations of VOC concentrations show that VOC concentrations are higher on weekdays than in weekends at the Xujiahui sampling site, suggesting that traffic condition and human activities have important impacts on VOC emissions in Shanghai. The evidence also shows that the major sources of isoprene are mainly resulted from gasoline evaporation at a particular time (06:00-09:00) in the busy commercial area. The results gained from this study provide useful information for better understanding the characteristics of ambient VOCs and the sources of VOCs in Shanghai.

Long-term variation of satellite-based PM2.5 and influence factors over East China.

With the explosive economic development of China over the past few decades, air pollution has attracted increasing global concern. Using satellite-based PM2.5 data from 2000 to 2015, we found that the available emissions of atmospheric compositions show similar yearly variation trends to PM2.5, even if the synchronization is not met for each composition, implying that the intensity of anthropogenic emissions dominates the temporal variation of PM2.5 in East China. Empirical orthogonal function analysis demonstrates that the dominant variability in the seasonal PM2.5 is closely associated with climate circulation transformation, incarnated as the specific climate index such as the Asia Polar Vortex intensity in spring, the Northern Hemisphere Subtropical High Ridge Position for the leading mode and the Kuroshio Current SST for the second mode in summer, the Asia Polar Vortex Area for the leading mode and the Pacific Polar Vortex Intensity for the second mode in autumn, the NINO A SSTA for the leading mode and the Pacific Decadal Oscillation for the second mode in winter. Therefore, apart from anthropogenic emissions effects, our results also provide robust evidence that over the past 16 years the climate factor has played a significant role in modulating PM2.5 in eastern China.

Long-term characteristics of satellite-based PM2.5 over East China.

With the explosive economic development of China over the past few decades, air pollution has become a serious environmental problem and has attracted increasing global concern. Using satellite-based PM2.5 data from 2000 to 2015, we found that the temporal-spatial variation of PM2.5 in East China is characterized by high concentrations in the northern part and low concentrations in the southern part of East China, and by being seasonally high in autumn and winter but low in spring and summer. We also found that the regional average PM2.5 concentration shows an approximative peak pattern over the last 16years, with the highest, 60.13µgm-3, and the lowest, 46.18µgm-3, occurring in 2007 and 2000, respectively. Despite obviously diminishing heavy polluted regions with a PM2.5 of >80µgm-3 after 2011, those cells dominated by natural background have still not recovered back to the clean level of 2000. These characteristics are valuable information to analyze the relative contributions of anthropogenic emissions and atmospheric conditions to the temporal-spatial variation characteristics of PM2.5.

Long-term trend of O3 in a mega City (Shanghai), China: Characteristics, causes, and interactions with precursors.

In recent years, ozone (O3) is often the major pollutant during summertime in China. In order to better understand this problem, a long-term measurement of ozone (from 2006 to 2015) and its precursors (NOx and VOCs) as well as the photochemical parameter (UV radiation) in a mega city of China (Shanghai) is analyzed. The focus of this study is to investigate the trend of O3 and the causes of the O3 trend in large cities in China. In order to understand the relationship between the O3 precursors and O3 formation, two distinguished different sites of measurements are selected in the study, including an urbanization site (XJH-Xujiahui) and a remote site (DT-Dongtan). At the XJH site, there are high local emissions of ozone precursors (such as VOCs and NOx), which is suitable to study the effect of O3 precursors on O3 formation. In contrast, at the DT site, where there are low local emissions, the measured result can be used to analyze the background conditions nearby the city of Shanghai. The analysis shows that there were long-term trends of O3 and NOx concentrations at the urban site (XJH) from 2006 to 2015 (O3 increasing 67% and NOx decreasing 38%), while there were very small trends of O3 and NOx concentrations at the background site (DT). The analysis for causing the O3 trend suggests that (1) the large O3 increase at the urban area (XJH) was not due to the regional transport of O3; (2) the measurement of solar radiation had not significant trend during the period, and was not the major cause for the long-term O3 trend; (3) the measurement of VOCs had small change during the same period, suggesting that the trend in NOx concentrations at the urban site (XJH) was a major factor for causing the long-term change of O3 at the urban area of Shanghai. As a result, the O3 and NOx concentrations from 2006 to 2015 at the urban area of Shanghai were strongly anti-correlated, suggesting that the extremely high NOx concentration in the urban area depressed the O3 concentrations. It is interesting to note that the anti-correlation between O3 and NOx was in an un-linearly relationship. Under high O3 concentration condition, the ratio of Δ[O3]/Δ[NOx] was as large as -1.5. In contrast, under low O3 concentrations, the ratio of Δ[O3]/Δ[NOx] was only -0.2. This result suggested that when O3 concentration was high, it was more sensitive to NOx concentration, while when O3 concentration was low, it was less sensitive to NOx concentration. This study provides useful insights for better understanding the causes of the long-term-trend of regional O3 pollution nearby Shanghai, and has important implication for air pollution control in large cities in China. Due to the fact that NOx and VOCs are not only precursors for O3, but also are important precursors for particular matter (PM). If reduction of NOx leads to decrease in PM, but increase in O3, the NOx emission control become a very complicated issue and need to carefully design a comprehensive control method.

Development of an on-line source-tagged model for sulfate, nitrate and ammonium: A modeling study for highly polluted periods in Shanghai, China.

An on-line source-tagged model coupled with an air quality model (Nested Air Quality Prediction Model System, NAQPMS) was applied to estimate source contributions of primary and secondary sulfate, nitrate and ammonium (SNA) during a representative winter period in Shanghai. This source-tagged model system could simultaneously track spatial and temporal sources of SNA, which were apportioned to their respective primary precursors in a simulation run. The results indicate that in the study period, local emissions in Shanghai accounted for over 20% of SNA contributions and that Jiangsu and Shandong were the two major non-local sources. In particular, non-local emissions had higher contributions during recorded pollution periods. This suggests that the transportation of pollutants plays a key role in air pollution in Shanghai. The temporal contributions show that the emissions from the "current day" (emission contribution from the current day during which the model was simulating) contributed 60%-70% of the sulfate and ammonium concentrations but only 10%-20% of the nitrate concentration, while the previous days' contributions increased during the recorded pollution periods. Emissions that were released within three days contributed over 85% averagely for SNA in January 2013. To evaluate the source-tagged model system, the results were compared by sensitivity analysis (emission perturbation of -30%) and backward trajectory analysis. The consistency of the comparison results indicated that the source-tagged model system can track sources of SNA with reasonable accuracy.

[A Numerical Study of Typical Heavy Air Pollution Episode of PM2.5 in Shanghai].

To analyze the characteristics and formation mechanism of a heavy air pollution episode in Shanghai City from January 23th to January 24th, 2013, the observed data of PM2.5 concentration and ground meteorological data and the WRF-Chem model were collected. The analysis revealed that the synoptic necessary mechanism of the heavy air pollution episode could be characterized by the following patterns: Accompanied with weak cold front activities, the city experienced weak winds (i. e. stable atmosphere) at first and then northerly winds (i. e. pollutant transport process ), causing the continuous increase and maintaining of pollutant concentration. The detailed results are shown as follows: Firstly, the stable atmosphere circulation pattern which lasted for 10 hours was not good for air pollution dispersion, as a result, local PM2.5 concentrations continued to increase and reached severe pollution level and the high concentrations maintained for 7 hours caused by the stable boundary layer (e. g. static surface winds and low level temperature inversion) during nighttime, and the average PM2.5 concentrations during the stable weather process was 172.4 µg · m⁻³. Secondly, the dispersion condition was slightly improved later on with the arrival of a weak cold front, the upstream pollution transportation occurred at the same time, leading to further increase of PM2.5 concentration (up to 280 µg · m⁻³), and the average PM2.5 concentration during the upstream transportation process was 213.6 µg · m⁻³. Numerical simulation with the WRF-Chem model showed that, average contribution of upstream transportation to local PM2.5 concentrations during the episode was 23% . Among them, the contribution during the stable weather and upstream transportation stage was 17.2% and 32.2% . Our results suggested that there were significant differences in the contribution of upstream transportation to the local PM2.5 concentration of Shanghai due to variation of weather conditions. Therefore, the government can design effective emission control strategy in advance taking pollution weather forecasting into account.

Synthesis and biological evaluation of 2,6-dichloropurine bicyclonucleosides containing a triazolyl-carbohydrate moiety.

A series of bicyclic nucleosides containing a triazolyl-carbohydrate moiety were synthesized and their antitumor activity in vitro for human cancer cell lines was also tested. Compound 11 was synthesized efficiently with 3,6-anhydro sugar 7 as raw material, while compound 7 was prepared from 1,2;5,6-di-O-isopropylidene-α-d-glucose. Compounds 12a-e were synthesized by treating compound 11 with alkynes, catalyzed by copper(I). After removal of the acetyl protecting groups, the target compounds 5a-e showed significant inhibitory activity against EC109, PC-3, MGC-803, and HGC-7 cell lines.